Manufacture of formates and oxalates.



A. LAcKMAn. 1 MANUFACTURE 0F FORNATES AND 0X`ALATES.

. .APPLICATION mso iuLY 24. 1917.

Patented July 50, 1918.

Y i SHEET HE T E :ssii l A. LACKMAN.

MANUFACTURE 0F FORMATES AND OXALATES..

APPLICATION FILED IULY24. IQII.

4 SHEETS-SHEET 2.

wig@ Mdm Patented July 30, 1918.

A. LACKMAN. MANUFACTURE 0F FORMATES AND OXALM'ES.

APPLICATION HLE'D JULY 24,1917.

Patented Ju1y'30, 1918.

4 SHEETS-SHEET 3.

wwfmrmfmw 52 MQL A. LACKMAN.

MANUFACTUBE 0E FORMATES AND OXALATES.

APPLICATION flLED JULY24. 1917.

DER LACKMAN, 0F BRADFORD, PENNSYLVANIA.

MANUFACTURE OF FORMATES AND 0XALATES.

Specification of Letters Patent.

Application iled July 24, 1917. Serial No. 182,534.

To all whom it may concern Be it known that I, ALEXANDER LACKMAN, a citizen of the United States, residing at Bradford, in the 'county of McKean and State of Pennsylvania, have invented certain new and useful Improvements in the Manufacture of Formates and Oxalates, of which the following is a specification.

This invention relates to the manufacture of foi-mates and oxalates and it comprises a process wherein sodium formate and sodium oxalate are successively and continuously produced from sodium hydrate with the aid of a gas containing'carbon monoxid, such gas being heldin contact with the material during the formate producing phase and during the oxalate producing phase, as in a process wherein powdered or granulated sodium hydrate (caustic soda) is moved as a thin traveling agitated stream through a tubular heated conduit in countercurrent against a stream of preheated gas as rich as possible in carbon monoxid, such gas carrying in a large part of the heat units necessary in the reaction, the travel of the sodium hydrate being continued until it is converted into formate, and then the formate is moved and agitated in a similar manner in a current of preheated and hot gas containing carbon monoXid, a part of the heat necessary for the reaction beingrhere also conveyed into the reaction Zone by means of such gas; and it also comprisesv certain details of operation in such a method; all as more fully hereinafter set forth and as claimed.

The manufacture of formate of sodium from sodium hydrate and gas containing C() is an old and well understood method. In operation however it suffers from certain inherent defects. It is an object of the present invention to obviate these inherent defects and render the operation simpler, more economical and more productive. y It has been known for many years that .CO

reacts upon sodium hydrate in the sense of the following equatlont- NaoH+co=NacooH- The reaction takes place under pressure fairly readily at comparatively low tem'- peratures, say, 150 to 220 C. But a very high gas pressure is necessary for good results and in order to hasten the action, many other expedients have been employed; generally in the line of increasing the surface Patented July 3o, 1918.

of the soda exposed to contact with the gas. For example, in the earliest embodiments of the method, the soda. was used in the form of soda-lime or was mixed with coal'or charcoal powder to give a maximum surface. Frequently the caustic soda was used in solution.

It has also long been known that sodium formate at a temperature around O0-450 C. breaks up by molecular rearrangement to form oxalate, the reaction going on in the sense of the following equatlom- It will be noted that in this action there is an evolution of hydrogen. While the reaction goes forward readily enough when the formate reaches and is at the correct temperature (under the particular method of operation) yet it is a very sensitive one. There is a. strong tendency for the sodium formate at'a somewhat lower temperature, at and below 360o C. to undergo a molecular change with production of sodium carbonate in the sense of the following equation eNacooHNazcoH-COJFH..

It will be noted that this reaction is at' tended with the evolution of CO 'and -I-Iz. In .making oxalateit is therefore necessary that the formate be brought` as quickly as possible to a high temperature without lingering at lower temperatures.

In 'lieu of attempting to heat massesl obtaining complete conversion under muc 1 l lower gas pressure and without the necessity of using an undue amount of gas. .The sodium forma-te so produced is sent through a similar conduit in the oXalate making phase in a similar way. By using agitated thin traveling streams of solid material'in both operations, it is easier to raise the material to the quite exact temperature required while at the same time high capacity of apparatus is attained. Further, I convey much of the heat necessary for the action to the solid material by the simple expedient of preheating the gases fed into the react-ion zone in each instance; this gas in the formate producing phase having also the function of furnishing CO. The same kind of gas that is usedrin making the formate is also used as an atmosphere in the oxalate forming phase. This offers the advantage that the formate producing phase and the oxalate producing phase may be allowed to overlap with resultant flexibility in the operation a-nd simplicity of apparatus. lVhile I shall hereinafter describe more particularly a process wherein the formation of sodium oxalate is the ultimate object yet I` wish it to be luiderstood that should sodium formate be desired the operation may be interrupted at the end of the formate producing phase.

In the formate production, water gas or blue gas" may be employed; i. c., gas made, by alternately blowing a coke or charcoal mass with air and wlth a current of'steam to furnish a gas containing about equal pro-y portions of CO and H2. Soft coal may be -used as an economical source of gases for the present purpose, a water gas generator being supplied with coke and operated in a.

well known manner; that is by alternately blowing with air to, heat it up and running with steam to furnish water gas. The gas obtained in the blowing operation (regenerator gas) may be used for carbonizing the soft coal to furnish coke, thereby incidentally obtaining a mixed gas 0f high heat value. Instead of using blue gas made as described or in other ways, ordinary producer gas may be employed.- 4This producer gas may be made by blowing ignited coal or coke with air or with air containing carbon plete installation for the manufacture suc' cessively and continuously of sodium formate. and sodium oxalate. In this showing Figure 1 is a diagrammatic plan view showing anapparatus comprising 'a unit of four sodium formate converters and a unit of four sodium oxalate converter;

Fig. 2 is a front elevation of vthe formate apparatus looking from left to right of Fig. 1.; feeding receivers and cross conveyer being omitted for clearness of illustration;

Fig. 3 is a rear elevation looking from lers are supplied 'bypipes converters.

right to left of element A in Fig. 1 and showing receivers and cross conveyer, but, omitting the shafts and pulleys of the converters;

Fig. 4 is a longitudinal section along line a-b of Fig. 1 of the formate apparatus.

A greater or less number of converters than those shown may form a unit.

The feeding andA discharging means of the oxalate apparatus are similar.

In the drawings and referringparticularly to Fig. 1,' gas rich in carbon monoxid, such as producer gas, mixedgas, water or blue gas, is supplied by a conduit l from a sourcenot shown to the system for reaction purposes. As shown in this view7 the formate apparatus is indicated by A and the oxalate apparatus by B.

As the temperatures required in the formate converters are not, high (about 220o C), I advantageously inclose these converters in a special heat-ing chamber 3 (see Fig. l) spa-ced away from a combustion chamber by a heat permeable wall 51, which may be made of lire brick. Through this heating chamber extend gas pipes 2 serving to supply the formate converters with preheated gas. -Communication with the interior of the converter l is at 10. 11 and 12. Heat is supplied to. a lowerA combustion chamber by gas burners 5 (see Figs. 2 and l). These gas burners` may be fed from gasometer g, Fig. 1, which serves to contain waste gases from the operation v'together with any excess of original gas. The burn# The combustion gases (see Fig. 1t) pass through downtake T at theend of the furnaces and fines S and 9 to the smoke stacks1 (Fig. l). Indicating thermometers 13 extend into these gas pipes and indicate the exact temperature of the preheated gas going into the The temperaturein the heating chamber can be regulated by supplying more or less gas to the burners through mechanically regulated gas' valves; by opening or closing the'dampers 8 in the fines S (Figs. l

and l) or by opening or closing the small doors '1l -(Fig. :2 In order to permit a further control of temperature in the heating chamber for the formate converters, these chambers may be provided with small supplementary venting stacks 15 which will giveV` enough draft to suck some cold air through the heating chamber in the event the temperature tends to rise too high. For

this purpose doors Hare opened.

The structure of the oxalate apparatus is much the same as is shown in Fig. l,- save that the brick wall 51 is shortened, allowing (Fig. 4)'.

The combustion gases go through the heat-l it is supplied to the whole system, the supply being regulated by valves 18 (see Fig. 2). As shown in.Fig. 2, the supply is to the formate converters but the oxalate converters `are similarly supplied. The valves communicating with the oxalate converters are omitted for the sake of clarity of illustration. Tail gases from both sets of converters are led to the gasometer through suitable gas conduits or pipes which may be closed by valvesl9 (see Fig. 1). In starting up the apparatus air contained in the converters may be released through small petcocks (not shown) placed on these pipes.

The formate converters are usually run under pressure and are provlded, for thisl purpose, with pressure regulating valves 20 (see Figs. 1 and 4.) These valves are set for the desired pressure. p gas fed in is regulated by valves 18. In the oxalate making loperation .the gas feeding valves of the preheating gas pipes of the oxalate converters are nearly closed, so that only a small stream of carbon monoxid containingI gasgoes through these pipes. In order to be sure that there is4 no leak, the

whole system'can be held under pressure for a test by closing the feeding valves. S0 long as the valves 19 are not opened and there' is no leak, the pressure remains constant. When assured thatnthere is no leak the vovens are iired. The. -indicating thermometers 21 (Fig. 2') are located in different places in the heating 'chambers and when the temperature in the formate ovens as well as in the oxalate ovens is reached, the process can be started.

Sodium hydrate powder is then dumped into the hopper 22 (Fig. l1) whence the cup elevator 23 lifts it to -the hopper 24 and from here it is dumped into the cross con-r veyer 26':,regulated by the damper 25. The cross lconveyer 26 charges the receivers 28, the charges being regulated by dampers 27, These receivers are cylindrical vessels tightly inclosed in another cast iron cylinder and here adapted to be rotated. They are driven by the shaft 29 and pulley 30 (Fig. 3). .There is only one open space in the lnner. cylinder of these receivers and when this open space is at its highest point it registers with the tube connection of the The amount of cross conveyer whereupon the sodium hydratepowder runs into the receiver. When the receiver' is turned with its open space down, the sodium hydrate is discharged linto the formate converterand theother ortion ofthe receiver seals the opening o the tube connection. In the converters the powderv is moved by a screw conveyer 4 or the like, through the heated tubes. Instead ofl using the rotary receiver,'cylinders with horizontalremovable rod and piston disksl can be used. These take and discharge the,

soduim hydrate and the sodium formate from the cross conveyer. Sincel the gas goingthrough the formate and oxalate converters is under more or less pressure, the

special means for delivering the sodium lry- -l drate to the formate converters and the sodium formate to theoxalate convertersv is very important. It makes possible the operation of both processes under definite pressures without loss of gas. The gas outlets 31 and 32 (Fig. 4) in the outer cylinder release the gas in the receivers when the opening space of the inner vessel reaches the outi)ets. 7The released gas goes to the furnaces y 3 2 Fig. 4 shows the converter 4, the shaft 32, stufling boxes 33 and drive pulleys 34. The caustic soda powder is moved through the formate converters against the carbon monoxid carrying gas and since the converter and gas are heated to about 220 C., the caustlc soda willsoon have the same temperature. The sodium hydrate powder being in only a thin layer in the converter and steadily moved it comes into very intimate contact with the preheated carbon monoxid gas, giving the most favorable conditions for converting the sodium hydrate into sodium formate. Only a low pressure of the gas in these converters is necessary to secure ecient absorption. .Further the outgoing sodium formate at the end of the converter comes into contactgwith the richest preheated carbon monoxid gas, which insuresconverted into formate before discharge.

' The'sodium formate is dischar ed at the end Yof the converters, through out ets dumping it 'into receivers .35 (Figs. 3 and 4). These receivers are similar in operation to the inlet receivers described, with the exception that dampers arenot necessary. The sodium formate removedby these devices from the converters goes Ato the cross -conveyer 36 (Figs. 3 and 4) .i The gas outlets 37 release .the gas from theA receivers and this gas is also piped tothe furnaces. Further, a gas outlet at the end of the cross conveyers (not shown in the illustration) may be connected with a jet to take away'hny gas which may escape.' It may be blown into the furstorage or is delivered through the chute 38 (Fig. 1) `and is -lifted by a cup elevator 39 to chute 40 and to hopper 41 of the oxalate apparatus B to be converted into sodium oXalate. l

Instead of mounting the formate ap aratus and oxalate apparatus at substantially the same level, the formate apparatus may be mounted above the oXalate apparatus, rendering possible some simplification of the conveying means used and also some simplification of the heating.

Describing now more particularly the cX- alate apparatus indicated as a Whole by B (Fig. 1) ,the sodium formate is delivered into the oxalate converters 42 in the same way as Ithe caustic soda powder is distributed to the formate converters. Fig. 4 serves equally as well as cross section of the oXalate apparatus under the present invention along line c-CZ, with the difference that the front .View with the charging means is at c and the back view with the discharging means of the sodium oXalate converter is at al and that the preheating gas vpipes 43 enter the chambers at the back end of the ovens at d and leave the ovens at the front end at c. The gases enter the converters Where the sodium formate is charged. The tail gas pipes 44 (Fig. 1) have no pressure regulating release valves but they are fitted with check valves-not shown-and the chambers have no air stacks (15), as the combustion gases go back through the heating chambers to the front of the furnace chamber and through lue 17 to the smoke stack.

The sodium formate entering the heated oxalate converters comes into contact with preheated gas of the same character as that used in the formate converters.

- Since this gas is preheated to about 440 C. it aids in quickly bringing the sodium formate which is moved through the converters from c toward al to the oxalate producing temperature; and since it is rich in carbon monoXid, any sodium hydrate which may have been left unconverted in the sodium formate apparatus'y will be here also converted into sodium formate vbefore the high temperature is reached. As the converters and the gas going with the sodium formate through these converters are both heated to about 440 C., the sodium formate cannot remain at 360 C. or below this temperature any length of time so that the dangerous temperatures are precluded and conversion ofthe sodium formateinto sodium carbonate is avoided. The conversion of sodium formate into sodium oXalate takes place uickly asrsoon as a temperature above 360 is reached. No sudden or tumultuous evolutionof large quantities of hydrogen can take place to give rise to explosions or troubles in the converter. The sodium formate moves through the converting Zone in successive small quantities, each of Which successively reaches the converting temperaf the sodium formate from the formate con- A verters and shown in Fig. 3. The end part of the cross conveyer 45 (Fig. 1) is jacketed and cooled with circulating water and the cooled sodium oxalate is discharged through the chute 4G into the hopper 47, whence it can be lifted to a place of storage or to an apparatus adapted to dissolve and decompose it with milk of lime to form calciumy oxalate and caustic soda, in the manner usual in the manufacture of oxalic acid. The tail gas coming from the formate converters and robbed of most of its carbon monoXid is led by pipes 48 into gas conduit 49 and through pipe 51 into the gasometer g. Similarly the tail gas from the oXalate convertersis led by pipes 44 into gas conduit 50and pipe 51 into the gasometer.

Both conduits 49and 50 are similarly fitted with valves 19 and check valves 53. The tail gas from the oXalate converters contains all the hydrogen coming from the conversion ofthe sodium formate into oxalate and mixes in pipe 51 with the tail gas from the formate converters, giving a mixed gas in the gasometer very well adapted for heating the apparatus. The surplus gas from the producers or generators or so much of this original gas as may be needed for heating purposes, may be added to the mixed as 1n the gasometer through conduit 52 Fig. 1).

To' control both processes samples of the discharged sodium formate as well as of the converted sodium oxalate, are taken and tested at intervals. To facilitate testing, holes tted With plugs are bored in the tube connections of f the discharging receivers, and the cross conveyer, large enough to introduce a small spoon for taking thesamples of the dumped converted products. processes are going correctly, if more or less sodium hydrate has to be charged, if the temperature of the chambers of the ovens and of the preheated gases has to be co1'- rected, whether the gas pressure in the formate converters should be lowered or raised, if the charges should be moved slower or Afaster through the converters and so on.

These tests will indicate if bothl K ylChis renders both processes exceptionally accurate and economical.

rl`he above description of the operation of the apparatus suliices to describe the several parts more particularly.

@ne advantage of the present process is that the supply of Waste gases or tail gases can be economically used for producing the heat necessary. The mixed tail gases from the format-e converters and oxalate converters give a mixed gas rich in heat units.

1What I claim is: g

l. The process of making sodium formate which comprises passing granular caustic soda through a tubular heated conduit in countercurrent against preheated gas containing CO. l

, 2. The process of making sodium oxalate which comprises transmitting granular sodium hydrate through a heated conduit in countercurrent to preheated gas rich in CO and transmitting the sodium formate produced through an externally heated tubularJ conduit in the presence of a flowing preheated gas containing CO.

3. The process of. making sodium oxalate which comprises passing granular sodium formate through an externally heated conduit as a traveling stream in the resence of a flow of preheated gas rich in O.

4. In the manufacture of formatos andl oxalates the process which comprises passlng av travelmg layer ofI granular caustic soda against a current of hot gases containing CO until the greater part of said sodav is converted into formate, and converting the so-treated material. into oxalate in the presence of suiicient .CO to convert residual soda into formate. l

5. In the manufacture of formates and oxalates the process which comprises transmitting granular caustic soda through a hot tubular retort against a current of CO-containing gases, removing it from the retort and transmitting it through a similar but hotter retort to produce oxalate, said similar retort being also supplied With'a current of v gases containing CO.

6. In the manufacture of formates and oxalates, the process which comprises transmitting sodium hydrate. continuously through tubular {ire-heated conduits in the presence of gas currents containing CO, such transmission first being under formate producing conditions and second'under oxalate producing conditions and the Waste gases from both operations being. used for heating said conduits.

In testimony whereof, I affix my signature hereto.

ALEXANDER LACKMAN. 

